Preparation of aromatics



Unite PREPARATION OF AROMATICS Charles Newton Kimberlin, J1., and William Judson Mattox, Baton Rouge, La., assignors to Esso Research and Engineering Company, a corporation of Delaware The present invention relates to a novel chemical process for preparing relatively pure aromatic compounds and naphthenic compound to carbonto carbon multiple bonds over a crystalline zeolite catayst' undenselectivecritical conditions. More particularly, the present invention relates to a novel catalytic process for converting cyclottes Pa Patented Mar. 21, .1961

In accordance with the. present invention, it has been found that aromatic compounds may be obtained in good atively mild conditions to develop the desired crystalline form. The crystalline alumino-silicate is then separated from the reaction solution as byfiltration and then washed with water, dried and activated by calcining. If desired;

a I the alumino-silicate may be ion exchanged before or after saturated compounds by transfer of hydrogen from a paraffins and cycloolefins, such as cyclohexane and cyclohexene, to aromatic compounds such as benzene in the presence of a crystalline metallic"alumino-silicate'having uniform pore openings between about 6 and 15 Augstrom units. in-part of Serial No. 656,183 filed May'l, 1957.

The production of aromatic hydrocarbons has-become extremely important in recent years in view of thedemands thereof as solvents, as chemical intermediates, and

The present application is a continuationsilica is '1/ 1 and the preferred reagent is sodium metasilicate. The concentration of the sodium silicate may be in the range of about to 300 grams of SiO per liter, preferably about 100 to 200 grams per liter.

as components in high'octane number motor gasolines;

Although large quantities of aromatics are currently being produced by coal distillation and especially by the hydroforming of petroleum naphthas, 'the'demand for aromatics still exceeds the supply. Accordingly, there is a definite need for new sources of aromatics and new or. improved methods of preparing aromatics It is the object of this invention to provide the art with a novel method for producing aromatics.

It is also the object of this invention to provide the art with a novel method for converting cyclic olefinic hydrocarbons into aromatics. j

It is a further object of this invention to'provide the art with asimple, effective method for converting low molecular weight or C to C olefins into lower boiling aromatics as well as higher boiling olefins intohigh molecular weight aromatics. g o

It isa still further object of the: present invention to provide a catalytic method for converting cyclic hydro carbons to aromatics by a hydrogen transfer process.

These and other objects will appear moreclearly from directly transferred between naphthenic compoundsand unsaturated compounds capable ofsaturation atone or more bonds, both double and triple.- Thus, the process .is suited to simultaneous conversion of naphthenes to aromatic compounds and the conversion of. olefins vto paraffins using solely the hydrogen removed from the naphthene. Similarly, if 'a cyclic olefin is employed as feed, a portion acts as hydrogen donor and is c onvert'ed to the aromatic, while another portion actsas acceptor and is converted to the corresponding saturated ring compound. a."

The composition of the sodium aluminate is less critical than that of the sodium silicate. Sodium aluminate having a ratio of soda to alumina in the range of 1 /1 to 3/1 may be employed, but it is p'referred to use those sodium aluminates having a relatively high ratio, say 1.5/1 soda to alumina ratio. The sodium aluminate concentration maybe in the range of from about. 40 to 400 grams A1 0 per liter, and preferably is. about 200 to 300 grams per liter. v

The amount of sodium silicate and sodium aluminate solution used should be such that the ratio of silica to alumina in the final mixture is in the range of 3/1 to 10/1, preferably about 4/1 to 6/1. dinarily effected at ambient temperatures and should be rapid and efficient as in the impeller zone of a centrifugal pump.

The mixture is thereupon passed to a heater zone'and heated to about to 250. F. or more. During'the timeof passage through, the heated zone, the reaction slurry undergoes crystallization to give the desired .struc- 1 ture. Atabout 210 F. crystal formation is completed in about ,3 to 24 hours. At higher temperatures shorter times are required for completion of the crystal 'formaf; tion, while at lower temperatures, somewhat longer time periods are required. After crystal formation of the precipitated sodium alumino-silicatehas been completed-the The physical and/or catalytic properties of the a'lumifi no-silicates may then be modified by base exchanging at least part of the sodium ions in the sodium' aluminosilicate with other ions. For this purpose, solutionsof w calcium or magnesium salts may be utilized or, if it" is desired to further increasethe catalytic activity or'vary the pore opening, the zeolite can be impregnated Lo r base exchanged with salts of chromium, molybdenum, nickel, cobalt; zinc, vanadium, zirconium, tungsten, metals from 5. 7 groups HA, IlB- VIB, VIIB and VIII of the periodic table, or other metalswhich also promote the fauna The mixing is or--' wherein Me is the metal and n is the valence of said metal.

Various ion exchanged alumino-silicates are conveniently prepared from water soluble salts such as CrCl NiCl2, CC1 CaCI ZnCl MgSO etc., by the following general procedure. Four hundred grams of zinc chloride (or sulfate) is dissolved in 1500 cc. of water. To this solution (at about 80 to 100 F.) 500 grams of the dry sodium alumino-silicate is added slowly with stirring. Occasional agitation is continued for about two hours. The liquid layer is then decanted, the aluminosilicate washed twice with distilled water, and a fresh solution of ZnCl (400 grams/ 1500 cc. H O) added and allowed to stand, with occasional shaking, in contact with the adsorbent for 2 to 4 hours. The aqueous layer is decanted and the adsorbent washed with distilled water until the wash water is free of soluble salts. The adsorbent is dried in an oven at 225 to 250 F. and then calcined at 850 F. for two hours. This procedure is adaptable to a number of variations, such as the use of alcohol-water solvents, etc., to increase the solubility of certain salts. 7

Cyclic hydrocarbons suitable for conversion to aromatics by the use of metallo-alumino-silicate catalysts will comprise a wide variety of saturated and naphthenic compounds, such as cyclohexane, cyclohexene, decalin, tetralin, phenylcyclohexane, dicyclohexyl, etc., and their homologues.

The reaction may be carried out at atmospheric pressure, although somewhat elevated pressures will usual- 1y be advantageous but preferably below about 750 p.s.i.g. Temperatures of about 350 to 850 F. will usually be suitable and in most instances a preferred range is about 400 to 750 F. Within these ranges of temperature and pressure, feed rates measured as w./hr./w. may vary from about 0.05 to about 5 depending upon the olefinicity of the feed, catalyst activity, and the desired level of conversion. Since the catalyst employed in these conversions is also a strong adsorbent for the aromatics produced, it will usually be preferred, in fixed-bed operations, to periodically interrupt the feed and recover the aromatics by suitable desorption, such as steaming followed by air-blowing to re-dry, evacuation, or purging.

EXAMPLE 1 [Temp 400 F.; pressure: atm.; CnHu/CoHm mol. ratio: 2.9]

Cyclohexane conversion, wt. percent of feed 12.0

Product yields, wt. percent of C l-I fed:

Benzene l Di-isopropylbenzene 1 23.1 18.9

Propane Refractive index 1.4835 (25 C.) boiling point 202 C.; literature values for 1,3-diisopropylbenzene: Bl. 1.48214; B.P. 203 C.

The diisopropyl benzenes formed in this experiment were produced by alkylation of the benzene initially formed. .T

EXAMPLE 2 In a series of experiments, cyclohexene was vaporized and fed at atmospheric pressure to a fixed bed of metallic alumino-silicate maintained at a-temperature of 400 F. The cyclohexene feed rate was 0.1 v./v./hr. Feed was discontinued after 9 to 10 volumes of efliuent/ volumes of catalyst had been collected. The adsorbed hydrocarbon was then recovered from the alumino-silicate catalyst by steam desorption and analyzed along with the unadsorbed efliuent. For comparison, the calcium, zinc, sodium and potassium forms of the zeolite were tested. For further comparison, a crystalline zeolite having the formula Na O.Al O .2SiO was employed. Here the pores had a uniform diameter of 5 Angstroms. The following tabulation summarizes the results of these evaluations.

Comparison of metal exchanged alumina-silicates as hydrogen transfer catalysts cyclohexene feed [Temp.: 400 F.; pressure: atm.; feed rate: 0.1 v./v./hr.]

Yields, Volume Percent Alumluo Test No. Silicate Catalyst Beozene+ Cyclo- Methyl Cyclo- Substituted hexane Cyclopentene Benzenes l pentane 1 Some phenyl cyclohexano and diphenyl formed, especially in tests 523 and 548.

These data show clearly the catalytic activity of alumino-silicates having large pore openings, the calcium, zinc, and sodium forms being catalytically active while the potassium form showed no measurable activity at the conditions used. The smaller pore zeolite, calcium 4A with 5 A. pore openings, gave only a very poor conversion. Thus, the catalytic activity of the metal exchanged alumino-silicates is dependent on both (1) pore openings of sufficient diameter to freely admit the reactants and also to permit desorption of the reaction products and (2) the molecular aflinity exhibited by the metal ion for the hydrocarbon reactants, this affinity, in turn, being related inversely to the atomic radius. Thus, in group IA sodium has an atomic radius of 0.95 A. and potassiumga value of 1.33 A., the sodium being the more active form of the 13A sieve for hydrogen transfer. Calcium being in group HA, and zinc, in group IIB, are not comparable on the basis of atomic radii.

What is claimed is:

1. A method for simultaneously eifecting the catalytic dehydrogenation of a naphthenic hydrocarbon to an aromatic and the catalytic hydrogenation of an olefin to paraflins which comprises contacting a stream consisting of at least one naphthenic hydrocarbon and at least one olefin with a hydrogen transfer catalyst at a temperature in the range of about 350 to 850 F., a pressure in the range of about atmospheric to 750 p.s.i.g. and a feed rate in the range of about 0.05 to 5.0 w./hr./w., said catalyst comprising a crystalline metallo-alumino-silicate having uniform pore openings of from about 10 to 13 Angstrom units and wherein the metal constituent is a metal selected from the group consisting of sodium, vanadium, zirconium, group IIA, IIB, VIB, VIIB and VIII of the periodic table.

2. The process of claim 1 wherein said catalyst has the empirical formula wherein Me is the metal constituent and n is the valence of said metal constituent.

3. The process of claim 1 wherein said catalyst has the formula Na O.A1 O .2.7SiO

4. The method of claim 1 wherein said naphthenic hydrocarbon is cyclohexane and said olefin is propylene.

5. An improved process for converting a cyclic olefinic hydrocarbon to an aromatic and a saturated cyclic hydrocarbon which comprises contacting a stream consisting of at least one cyclic olefinic hydrocarbon with a hydrogen transfer catalyst at a temperature in the range of about 350 to 850 F., a pressure in the range of about atmospheric to 750 p.s.i.g., and a feed rate in the range of about 0.05 to 5.0 w./hr./w., said catalyst comprising a crystalline metallo-alumino-silicate having uniform pore openings of from about 10 to 13 Angstrom units and wherein the metal constituent is a metal selected from the group consisting of sodium, vanadium, zirconium, group IIA, IIB, VIB, VHB and VIII of the periodic table.

6. The process of claim 5 wherein said cyclic olefinic hydrocarbon is cyclohexene.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Breck et aL: Jour. Amer. Chem. Soc., vol. 78, No.

15 23, Dec. 8, 1956, pp. 5963-5971 (page 5964 only relied Physical Properties of Linde Molecular Sieves (Types 4A, 5A, 13X), Form 9947 (1 page), Linde Air Products Co], 30 East 42nd Street, New York 17, New York UNITED STATES'IEPATENT OFFICE CERTIFICATE OF CORRECTION Patent No a 2, 976,331 March 21, 1961 Charles Newton Kimberlin, Jr., et ale It is hereby certified that error appears in the above numbered patent req'iiring correction and that the said Letters Patent should read as corrected below Column 3,- lines 4 and 5 the formula, each occurrence, instead of as in the patent Me O.Al o .2.7SiO

n Signed and sealed this 7th day of December 1965.

and column 4, lines 74 and 75, I

should appear as shown below (SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER AI testing Officer 

1. A METHOD FOR SIMULTANEOUSLY EFFECTING THE CATALYTIC DEHYDROGENATION OF A NAPHTHENIC HYDROCARBON TO AN AROMATIC AND THE CATALYTIC HYDROGENATION OF AN OLEFIN TO PARAFFINS WHICH COMPRISES CONTACTING A STREAM CONSISTING OF AT LEAST ONE NAPHTHENIC HYDROCARBON AND AT LEAST ONE OLEFIN WITH A HYDROGEN TRANSFER CATALYST AT A TEMPERATURE IN THE RANGE OF ABOUT 350$ TO 850$F., A PRESSURE IN THE RANGE OF ABOUT ATMOSPHERIC TO 750 P.S.I.G. AND A FEED RATE IN THE RANGE OF ABOUT 0.05 TO 5.0 W./HR./W., SAID CATALYST COMPRISING A CRYSTALLINE METALLO-ALLUMINO-SILICATE HAVING UNIFORM PORE OPENINGS OF FROM ABOUT 10 TO 13 ANGSTROM UNITS AND WHEREIN THE METAL CONSTITUENT IS A METAL SELECTED FROM THE GROUP CONSISTING OF SODIUM, VANADIUM, ZIRCONIUM, GROUP IIA, IIB, VIB, VIIB AND VIII OF THE PERIODIC TABLE. 